JP5303280B2 - Method and apparatus for simultaneous high-speed acquisition of multiple images - Google Patents

Abstract

A method and apparatus for simultaneous high-speed inspection and acquisition of multiple data channels is provided. The method and apparatus enables inspecting semiconductor wafers and reticles and comprises converting a single image region into two image sections, reorienting one image into a transposed configuration enabling simultaneous scanning of two inspected object locations with a single sensor, and controlling acquisition parameters for a second image by using information collected from a first image in a feedback arrangement. The design provides a dual-linear or time-delay-integration sensor operating in a split readout configuration mode to simultaneously provide data from two regions of the sensor using two sets of readout circuitry.

Description

  The present invention relates generally to the field of automated high-speed image processing systems, and more particularly to electro-optical inspection and metrology systems for semiconductor wafers and reticles.

  Semiconductor wafer and reticle inspection instruments are continually improved to address the evolving problem of inspecting increasingly smaller features. New device structures, materials, related lithographic techniques, and rapid advances in reticle expansion strategies for circuit development are adding tremendous momentum to circuit complexity. In addition to advances in manufacturing materials and technology, increased complexity due to smaller features has placed more demands and additional requirements on the semiconductor silicon wafer inspection process. In particular, such materials and techniques create new types of defects and noise sources that dramatically increase the number of critical defects and make them more difficult to detect.

  To meet these demands, today's industrial inspection and measurement image processing systems can collect information on one or more channels corresponding to both static image processing and fast scan defect detection systems. Yes. As used herein, “channel” or similar term refers to image processing mode, brightfield and darkfield image processing, large / small signal readout, multispectral image processing, and transmission / reflection. Including, but not limited to, simultaneous image processing and broadband / narrowband optical image processing modes. Multimodal inspection is increasingly required throughout the industry to ensure optimal detection of the greatest range of defect types.

  For this reason, manufacturers currently produce inspection systems that can support multiple configurations that affect a wide range of image acquisition modes, and optimize one or more channels for specific inspection applications. Provide system solutions to collect information on For example, a wafer surface inspection system uses a dark-field image processing mode to detect particles such as dust scattered extensively on a smooth and uniform surface, while using a bright-field image processing mode to detect spots and stains. Other surface contamination can be identified.

  Conventionally, in a wafer inspection system, a sensor that inspects an object using a die-to-die or die-to-database inspection technology, such as a delay integration (TDI) sensor, etc. Is adopted. Collecting information for one or more channels during the inspection process can be technically difficult and can be particularly time consuming. Performing multiple inspections in combination with taking a specific measurement significantly increases the total inspection time and cost.

  Accordingly, an inspection architecture and design employing one or more detection devices is provided, the inspection design providing image acquisition that is robust and reliable and available in multiple image processing modes, and It would be advantageous to overcome the disadvantages associated with conventional systems used to perform mode checking.

US Pat. No. 7,126,699

  According to a first aspect of the design, a sensor is provided that is configured to receive light energy for the purpose of inspecting a sample. The sensor includes a first detection region configured to receive first channel image data from the sample and a second detection region configured to receive second channel image data from the sample. In addition, the sensor is connected to the first area and is configured to read image data of the first channel from the sensor, and connected to the second area and from the sensor. And a second readout circuit configured to read out the image data of the second channel from the sensor simultaneously with the readout of the image data of the first channel.

  According to a second aspect of the design, a system for performing simultaneous dual channel inspection of a sample is provided. The system is configured to receive at least one illumination device configured to supply light energy to the sample and to receive two channels of light energy from the sample and to change the direction of light energy of the one channel. An orientation optical element configured to provide light energy of a redirected channel and light energy of a non-redirected channel, light energy of the redirected channel, and A sensor configured in a concise manner to receive and simultaneously process light energy.

  The foregoing and other advantages of the present invention will become apparent to those skilled in the art from the following detailed description of the invention and the accompanying drawings.

  The present invention is described in the accompanying drawings for purposes of illustration and not limitation.

  This design uses a TDI sensor to scan a sample such as a semiconductor wafer. The TDI sensor receives data transmitted in two separate configurations, such as bright field data and dark field data, and passes the two sets of data from both sides of the TDI sensor to processing hardware and software. Previous TDI bi-directional sensors utilize only one side of the TDI sensor and one set of associated hardware in a unidirectional path, and the other side of the sensor when the path is established in the other direction. And the second set of associated hardware. This design uses both sides of the sensor and two sets of associated hardware simultaneously to scan in two modes in one pass. This dual channel implementation is accomplished by utilizing a novel arrangement of lenses, reflective surfaces, relays, and other components to provide the TDI sensor with two channels of data for a single surface. Is done.

System Configuration Overview This design description presents a method and apparatus for automatic high-speed image processing. Although this design may be utilized in a variety of environments and applications, this specification will focus on a semiconductor wafer or reticle inspection environment. One embodiment of this design is a semiconductor wafer inspection system or method suitable for inspecting the surfaces of masks, reticles, and wafers utilized in the semiconductor industry, for example. The design can utilize one or more illumination sources (ie, image modes) to generate one or more images of the sample or wafer being inspected.

  FIG. 1A shows the components and interfaces of this design in the inspection system 100, and the particular embodiment shown in FIG. 1A allows for inspection of semiconductor wafers, photomasks, and reticles. The inspection system 100 in this embodiment includes an illumination system 101, an inspection object 102, and a sensor 103 that generates an image data response representing a plurality of image processing modes. Although the illumination system 101 may include one or more illumination sources, when a plurality of illumination sources are provided, each light source irradiates the inspection object 102 with light energy having different spectrum and coherence characteristics.

  When the inspection object 102 reflects, transmits, or scatters light energy, the imaging optical element 108 transmits the light energy to the sensor 103. The sensor 103 simultaneously generates outputs corresponding to two individual image data responses or image data signals of the inspection object 102. This design can send the output signal generated by the sensor 103 to the data acquisition unit 104 to capture the sensor output. Next, the data acquisition unit 104 may send the acquired signal to the data processing unit 105 that analyzes the image in real time. The data acquisition unit 105 can store the signal output in the storage unit 107 and record sufficient image data for later data set analysis. Further, the data storage unit may store inspection information and measurement information used for die-to-database analysis by procedures well known to those skilled in the art. The control display unit 106 can provide user interaction and inspection system status suitable for recording the image signal generated by the sensor 103. Furthermore, the control display 106 may provide manual or automatic real-time feedback control for acquisition, analysis, data processing, storage, and reporting of acquired inspection and measurement results.

  Although a plurality of elements are illustrated, the data acquisition unit 104, the data processing unit 105, and the control display unit 106 may be replaced by an acquisition unit, a processing unit, And a single computer device that performs the function and purpose of the control display unit, or a set of distributed computer devices.

  A schematic diagram of the inspection system 100 showing the flow of information and the main system components for simultaneously collecting multiple images on one sensor according to this design is shown in FIG. 1B. The design may include an image forming mechanism, a sensor, and a data acquisition unit to support one or more light sources and an illumination relay unit constructed using at least one imaging lens. Configured. The design further includes a sensor.

  This design generally provides simultaneous support for two light source paths through the inspection system 100. FIG. 1B presents several possible foundations that feature different aspects of the design. Referring to FIG. 1B, the first channel illumination source 109 (eg, dark field channel) can emit light energy or a luminous flux, change the direction of the light energy, and send it to the illumination relay unit 115. Although the present design can accommodate various illumination modes, for the example of FIG. 1, the case where the illumination source of the first channel provides dark field image processing will be described here. The first channel illumination relay unit 115 may include at least one of one or more reflecting surfaces, a beam splitter, a reflector, a polarizing lens, and an illumination imaging lens relay array. The second channel illumination source 110 can emit light energy or a luminous flux, change the direction of the light energy, and send it to the illumination relay unit 120. In this example, the second channel illumination source provides bright field image processing. The second channel illumination relay unit 120 may include at least one of one or more reflecting surfaces, a beam splitter, a reflector, a polarizing lens, and an illumination imaging lens relay array.

  Further, the illumination source or the image processing mode is not particularly limited, but bright field and dark field image processing, large signal / small signal readout, multispectral image processing, transmission / reflection simultaneous image processing, Broadband / narrowband optical image processing modes and any combination thereof may be included. Some elements may also be shared between lighting paths.

  The first channel illumination relay unit 115 can collect the light energy emitted from the first channel illumination source, and can project the light energy or light flux onto the inspection object 130. Further, the second channel illumination relay unit 120 can collect the light energy emitted from the second channel illumination source, and can simultaneously project the light energy or light flux onto the inspection object in combination with the illumination of the first channel.

  In this configuration, the design provides simultaneous exposure of the inspection object 130 using two image processing modes. This design can collect light energy transmitted, reflected, or scattered from the inspection object 130 (that is, the sample under inspection) in the image relay unit 140. The image relay unit 140 can collect light energy and divide or separate the light energy into two separate channels or image processing modes. The image relay unit 140 can send the aforementioned divided energy to one or more image processing mode relay units. The image relay unit 140 may send dark field light energy to the first channel image mode relay unit 155. Similarly, the image relay unit 140 may send bright field light energy to the second channel image mode relay unit 160.

  The first channel image mode relay unit 155 receives the reflected dark field light energy from the image relay unit 140 and delivers or projects the reflected dark field light energy to the sensor 170. The image relay unit 140 and the image mode relay units 155 and 160 include any combination of at least one of a mirror, a beam splitter, a reflector, a polarizing lens, and a lens relay unit or another relay element. It's okay.

  Sensor 170 may include, but is not limited to, a dual linear sensor, a delay integration (TDI) sensor, or any other collection device suitable for achieving the purpose of sensor 170. The sensor 170 outputs the detected information simultaneously as individual image data from a plurality of readout circuits (not shown in FIG. 1). In this overview, the design provides a dark field response as image data at point 180 and a bright field response as image data at point 190.

  FIG. 1 is a diagram showing an outline of a system that can adopt this design. Important features of this design include providing light energy corresponding to one or more image processing modes and transferring the resulting information from the system as two separate images. Furthermore, the present design organizes independent image data obtained from the two illumination sources and adjusts so that the dark field image and the bright field image in this example reach the sensor 170 simultaneously.

Sensor configuration This design allows a TDI sensor to receive data on two separate channels, such as a bright field channel and a dark field channel, and to pass the received data to processing hardware and software from both sides of the TDI sensor. adopt. Conventional TDI sensors utilize one side of the sensor and a set of associated hardware in a unidirectional path, and the second side of the sensor and the second when the path is formed in the other direction. It used the related hardware of the set. The design scans in two modes in one pass, utilizing both sides of the sensor and two sets of associated hardware.

  In this configuration, a single sensor can provide simultaneous readout as a function of two illumination sources and can generate a separate output data stream for each image incident on the sensor 170. This design provides improved analysis without requiring additional time to perform two or more tests on the test object 130.

  The schematic diagram of the conventional bidirectional TDI sensor 200 for image acquisition shown in FIG. 2 shows an on-chip readout circuit along each side of the bidirectional TDI sensor 200. As shown in FIG. 2, the bidirectional TDI sensor 200 can generate a signal output from unidirectional scanning in either the forward or reverse scanning direction. In the positive scan direction, the bidirectional TDI sensor 200 receives light energy reflected from the inspection object 130 and forms an image 210 representing the received energy. The forward scan produces a signal output at a plurality of individual amplifier circuits 220. Data collected from the entire image sensor area 210 generated from the scanning in the forward direction is manifested in the forward reading circuit 240 as an output.

  The forward readout circuit 240 can send the aforementioned output to a data acquisition system (not shown in FIG. 2) that captures the signal generated by the bidirectional TDI sensor 200. Also, reverse scanning produces a signal output in a plurality of individual amplifier circuits 230. Data collected from the entire image sensor area 210 generated from the backward scan is manifested in the backward readout circuit 250 as an output. The reverse readout circuit 250 can send the aforementioned output to a data acquisition system (not shown in FIG. 2) that captures the signal generated by the bidirectional TDI sensor 200. That is, only one side of the TDI sensor 200 is read at a time. The signal collected by the data acquisition system may be compared to other stored or processed image data or known design information to confirm the quality of the sample or wafer.

  FIG. 3 shows a schematic diagram of the divided read TDI sensor 300 configured in the divided read operation mode. This figure shows an on-chip readout circuit that is continuously enabled on each side of the sensor. The split readout TDI sensor 300 can acquire two separate sequential image streams simultaneously by providing a signal output from scanning the inspection object 130 in a single direction (eg, positive direction). In this example, the split readout TDI sensor 300 receives dark field light energy reflected from the inspection object 130 and forms an image 310 representing the received dark field energy. A single positive scan produces an output corresponding to the dark field response via a plurality of individual first amplifier circuits 330. Data from the entire image detection area 310 appears as a first image “forward” readout line 350 as an output. The first image forward readout line 350 can send the aforementioned output to a data acquisition system that captures the signal generated by the split readout TDI sensor 300.

  Furthermore, the device operation generally scans the same region of the sample or wafer, or optionally different regions simultaneously, along with the forward scan used to generate the first image, on the split readout TDI sensor 300, It is configured to generate two independent images. In one embodiment, light energy representing the second image can be obtained using a mirror array that can be split into two images on the middle field plane and change the direction of one of the images.

  The mirror / reflecting surface array collects, sends out the resulting image configuration information, irradiates the second illumination mode to the TDI sensor 300 in the split mode, and can subsequently send it out of the TDI sensor 300 It is something to do. The following paragraphs describe specific details including the optical arrangement of this design. This optical arrangement collects information from a single scan in either direction and produces output data that enters the sensor in two opposite directions and is shown in FIGS.

  In this example, the split readout mode of operation allows the TDI sensor 300 to receive the bright-field light energy of the second channel, which is the second image in the region 320 based on the received bright-field energy. Form. The forward scan produces a bright field response signal output in a plurality of individual amplifier circuits 340. Data generated from the entire image sensor region 320 is manifested in the second image forward direction readout circuit 360 as an output. The second image forward direction readout circuit 360 can send the aforementioned output to a data acquisition system that captures the signal generated by the TDI sensor 300. The signal collected by the data acquisition system may be compared with other stored or processed image data or known design information to perform the inspection process. By the divided mode operation of the TDI sensor of this design, high-speed acquisition and high sensitivity of two images can be realized from a single scan of the inspection object 130.

  Thus, the split readout TDI sensor 300 of FIG. 3 can be used to scan two individual images or two identical images, if the image scan is properly configured or oriented, the data is , Collected by both sides or regions 310 and 320 of the sensor 300, and through a plurality of individual first amplifier circuits 330 and a plurality of individual second amplifier circuits 340, respectively, Data can be continuously sent to the two-image readout line 360. Thus, in contrast to the conventional configuration of FIG. 2, in the configuration of FIG. 3, all the components (amplifier circuit and readout line) associated with the divided readout TDI sensor 300 are used simultaneously, Scanning throughput can potentially be increased and overall inspection performance can be improved.

  FIG. 4 shows one embodiment of this design in which two regions of a 401 sample or wafer are imaged on the sensor 410. The two regions may include a single region of the sample or wafer that is imaged at different times and in different ways, for example, using different wavelengths of light energy. One or more regions to be examined are shown as arrows to indicate the orientation of the regions to be joined at different points of the sequence. Specifically, the second image in which the head is shown as a bright arrow is separated from the first image in which the head is shown as a dark arrow at a point on the reflection surface 404 and reaches the sensor 410. Is changed. As described above, the illumination system (not shown) may be a lamp-based system in which light is illuminated onto the system using, for example, a beam splitter known in the field of microscope design.

  The upper surface of the image to be inspected in this embodiment is shown in the sample field 414 including the first area 420 and the second area 421. The direction of scanning is indicated by arrow 411. Light energy from the illumination system may enter the region 420 and be reflected or scattered, collected by the lens 402, and further focused by the lens 403. For the second region 421, the illumination can have different spectral or polarization characteristics, which is the case for a light transmissive object such as a reticle through which light is transmitted from the sample. This arrangement can collect both image areas simultaneously.

  Therefore, the target field 414 of the image processing system exists at the position 401. This image processing system divides the sample field 414 into a first partial field 415 and a second partial field 416 and, in this embodiment, relays these fields to the image position on the sensor 410 via the focusing lens 409. . Since the reflective surface 404 divides the target field 414 into two regions, each partial field includes only one region 420 or 421. For the sake of clarity, the two partial fields 415 and 416 of the image are shown without overlapping, but the location of the regions 420 and 421 is such that the partial fields are located close together in the image plane of the sensor 410. In addition, the reflection surface 406 may be used for adjustment.

  When the inspection target field 414 moves in the direction indicated by 411, in the case of the forward path of FIG. 4A, the scanning directions of the two areas in the sensor 410 are shown at the top of the figure. In this case, partial field 415 moves in direction 412 and partial field 416 moves in direction 413. The ray path 424 specifies the approximate alignment of the two regions 420 and 421 on the sensor 410.

  Also for the reverse path example of FIG. 4B, the scanning directions of the two regions on the sensor 410 are shown. In this reverse path case, partial field 415 moves in direction 423 and partial field 416 moves in direction 422. The ray path 425 specifies the approximate alignment of the two regions 420 and 421 on the sensor 410. In this way, the direction of the scanned area can be controlled based on the orientation of the image projected on the sensor. This reverse path case and the orientation of the image on the sensor can be achieved by changing the angle or position of the reflective surfaces 406 and 408 as shown in FIG. 4B.

  In the scanning mode operation using the reverse direction path, the position of the sample in the first image area 420 moves during the scanning, and then the image is formed in the second image area 421. Thus, the two image areas can inspect or scan the same target position. After adjusting for the data collection time delay between the two regions, the design can provide a comparison of a single location on the object utilizing two image processing modes.

  FIG. 5 illustrates an embodiment similar to FIGS. 4A and 4B, but here shows an alternative method of changing the scan direction to change the orientation of the image on the sensor. The sample placed at 501 is shown as two arrow heads with different orientations, and is imaged on the sensor 508 at the image position by the lens 502, the additional relay lens group, and the reflecting surface. The relay positions 505 and 506 include a plurality of reflecting surfaces 505a, 505b, and 505c, and 506a and 506b, and divide the image area and change its orientation for reception by the sensor 508. In one example, a labeled reverse path and reflective surfaces 530 and 531 are utilized for the optical repeater. In normal operation, ie in the reverse path, light energy is incident on the sample and received by the lens or optical element 502. Next, the optical energy is sent to the reflecting surface 530, the reflecting surface 531, the lens 550, and the relay positions 505 and 506, as indicated by the solid line. After passing through relay positions 505 and 506, light energy reaches sensor 508 through lens element 551 and focusing lens element 507 in the orientation shown. Accordingly, the reflecting surfaces 520, 522, and 521 are not disposed, and do not receive, reflect, or transmit the light energy of the illustrated forward direction path.

  Three additional reflecting surfaces 520, 521, 522 are provided in the system to change the scanning direction. These reflecting surfaces may be fixed to one pedestal and moved to a predetermined position as one unit in order to realize comfortable mechanical switching in the scanning direction. When these three reflective surfaces are utilized, the positive path operates and the two original reflective surfaces 530 and 531 are not utilized. Several alternative optical designs may be employed for the selection of light energy between this reverse and forward direction. However, for optimum performance, the length of the optical path from the reflecting surface 520 to the reflecting surface 522 must be the same in both configurations, so that it does not change even if the scanning direction of the image changes. . That is, the distance of the dotted line in FIG. 5 from the reflecting surface 520 in the positive direction path to the reflecting surface 522 via the reflecting surface 521 is from the position of the reflecting surface 520 to the reflecting surface 522 via the reflecting surface 530 and the reflecting surface 531. It is the same as the optical distance along the solid line (reverse path) to the point. With the same optical path length, it is possible to suppress or eliminate the need to correct relative changes in image quality between paths, for example, relative changes in focus and / or magnification. Since no further changes in image alignment are generally required, the difference in image quality due to lens aberrations when the scan direction changes from forward to reverse in the arrangement of FIG.

  Again, the sample surface 560 is shown with two scanning regions 561 and 562, which are supplied to the sensor 508 depending on the path used. When the reflective surfaces 520, 521, and 522 are arranged and used (forward direction path), the scanning direction shown as the scanning direction 510 is assigned to the scanning direction 511 in the sensor 508. When the reflective surfaces 530 and 531 are disposed and used (reverse direction path), the scanning direction 510 is assigned to the scanning direction 512 in the sensor 508. The midway direction is indicated at point 523 for the forward path and at point 533 for the reverse path.

  Accordingly, as shown in FIGS. 4A, 4B, and 5, in general, depending on the orientation of the components in the optical array including at least one of a lens, a beam splitter, and a reflective surface, the sensor 410 or The resulting light energy applied on the surface of the sensor 508 can propagate in a direction different from the scanning direction. As shown in FIG. 5, in a forward scan 510 of the sample surface 560 having a region 561 and a region 562, at the sensor 508, the region 561 is scanned in the direction 511, ie, to the left, and the region 562 is in the direction 511, ie, It will be scanned to the right. Thus, for both images of the sample surface scanned in the normal or reverse sample scan direction, the data travels outward at the TDI sensor.

Various Sensor Designs FIG. 6 schematically illustrates a dual linear sensor 600 that includes two 1 × N line sensor subarrays that are spatially separated and integrated. FIG. 6 shows an on-chip readout circuit along each side of the sensor. The dual linear sensor 600 can acquire two scanned images simultaneously, and each subarray can operate independently of each other. In addition, the design can transmit an output or control signal generated from one side of the dual linear sensor 600 that is exposed on the second side of the dual linear sensor 600. It is sent for the purpose of controlling and changing the output parameters. Each 1 × N line sensor sub-array can collect image data only one pixel wide. Collecting 1 pixel wide image data in at least one sub-array eliminates image redirection requirements and mitigates other related acquisition and processing effects that may blur the image. . In this configuration, the dual linear sensor 600 can record scanned image data from the inspection object 130 using two auxiliary regions of the sensor. This auxiliary region can simultaneously scan the same position on the inspection object 130, and this scanning is not particularly limited, but includes an image processing mode, an illumination source, an illumination level, a wavelength, a spectral range, Different settings are utilized for polarization and / or other illumination characteristics.

  The dual linear sensor 600 receives light energy from the inspection object 130 in the form of a 1-pixel wide first image 610 representing this light energy. The data of the first image 610 may generate a signal output in one or more individual amplifier circuits 630. Data representing the first image 610 is manifested in the first line readout circuit 650 as an output. The first line readout circuit 650 can send the aforementioned output to a data acquisition system (not shown in FIG. 6) that captures the signal generated by the dual linear sensor 600.

  Further, the same scan that generated the first image can also generate a second image data stream from the dual linear sensor 600. This design can obtain the reflected energy representing the second image using the mirror arrangement described above. The independent auxiliary region allows the dual linear sensor 600 to receive the light energy reflected from the inspection target 130 and form a second image 620 having a width of 1 pixel based on the received energy. . Scanning in this manner using the above-described arrangement produces signal outputs for a plurality of individual amplifier circuits 640. The generated data representing the second image 620 having a width of 1 pixel is manifested in the second line readout circuit 660 as an output. The second line readout circuit 660 can send this output to a data acquisition system (not shown in FIG. 6) that captures the signal generated by the dual linear sensor 600. The signal collected by the data acquisition system may be compared to other stored images or known design information to perform the inspection process.

  Further, in the present design, a time delay may be introduced between the time when the first auxiliary area scans the position on the inspection object 130 and the time when the next auxiliary area scans the same inspection object 130. In this configuration, the output from the first auxiliary area can provide information to the on-chip control logic and thus provide a mechanism to change the acquisition parameters employed in the next auxiliary area. For example, the control circuit 670 can supply the output signal generated by the amplifier circuit 640 to the amplifier circuit 630. This design controls the first line readout circuit 650 in the form of a signal output generated by the amplifier circuit 640 by observing the characteristics of the inspection object 130, and changes the exposure time, amplifier gain, Allows you to manipulate acquisition parameters. For example, in order to remove the saturation effect and improve the dynamic range of the acquisition system, the first auxiliary region measures the signal reflected from the inspection object 130 and the resulting control over the exposure of the next auxiliary region. Provide a signal.

  FIG. 7 is a diagram schematically showing the M × N divided readout TDI sensor 700 set in the divided readout operation mode. The specific mode shown in FIG. 7 has a large auxiliary area on one side of the bidirectional TDI sensor. This is a configuration in which a small auxiliary region is adopted on the second side of the divided readout TDI sensor 700. By setting image auxiliary areas with different sizes, it is possible to optimize sensitivity and dynamic range, and to support two illumination sources with different characteristics (for example, high-intensity illumination source and low-intensity illumination source) Can do. Utilizing a large number of pixels in the auxiliary region of the high-sensitivity image channel 710 improves signal integration, while utilizing a small number or only a single line of pixels in the auxiliary region of the large signal image channel 720. As a result, signal integration can be suppressed and a large signal can be detected without saturation. By changing the size of the auxiliary region for each image channel, the design uses an improved dynamic range depending on the ratio of the number of integrated stages, and allows large and small signals of extreme magnitude from the region. It can be measured reliably.

  This design allows the most suitable output image data signal to be selected from only the first circuit 730 or only the second readout circuit 740, while ignoring the other outputs or selecting both outputs. Image data signals are combined so that a composite image can be formed. In one configuration, dark field energy may be sent to a large auxiliary area 710 while bright field energy may be sent to a small auxiliary area 720. With the function of selecting an appropriate integration ratio, an optimal inspection can be realized using different image processing modes in a single inspection scan.

  The case of choosing the right integration ratio occurs because the selected image processing mode produces a large difference in the image signal as seen in darkfield and brightfield image processing when using a single illumination source. This is the case. The dark field image mode can generate a lower signal for a particular inspection object 130 pattern that does not diffuse light energy efficiently. In this example, the high sensitivity image channel 710 provides dark field image processing for areas that detect lower signals, and the low sensitivity large signal image channel 720 provides bright field image processing for areas to be examined.

  The second case explaining the use of the appropriate integration ratio selection occurs when the selected image processing mode is found in wideband spectrum image processing and narrowband or multiline spectrum image processing. This is a case where such a significant difference is generated in the image signal. The total signal available from the broadband spectrum can be much larger than for narrowband or line filter light sources. In this design, a high sensitivity image channel 710 is used for the narrowband filter light source to provide the most effective utilization of the available illumination reflected from the object 130 to be examined. When illuminating using two different light sources, for example, when using a lamp light source and a laser light source together, the brightness (ie, light energy) of each light source can be completely different. To absorb luminance differences, the high sensitivity image channel 710 may collect reflected light generated from light sources with lower light energy, and the low sensitivity large signal image channel 720 may be generated from light sources with higher luminance. The reflected light may be collected.

  Furthermore, if different regions of the inspection object 130 react at significantly different reflected and scattered light levels when illuminated, a highly optimized inspection for these different regions can be performed by selecting an appropriate TDI integration ratio. It can be realized with a single scan. As described above, in such a configuration, different sizes (M × N), approximately equivalent sizes (M × M), lines (M × 1, 1 × N, or 1 × 1), or other arrangements of A TDI sensor 700 having two regions may be employed. In this case, a plurality of regions in which the dynamic range of the TDI sensor 700 can be improved by using different size configurations and the number of integrated stages or the image widths are different. Can be used to provide sensitivity control.

  A schematic diagram of an inspection system 800 with two illumination sources according to one aspect of the design is shown in FIG. In this configuration, the two illumination sources and the complementary illumination relay system are arranged with a common imaging lens and sensor. In this example, the first light source is used for bright-field image processing, and the second light source is used for dark-field image processing. The illumination source 810 may irradiate light energy or light flux, for example, and the image processing system sends bright field light energy toward the first channel illumination relay unit 815 (that is, the first channel illumination and the imaging lens). Good. The illumination relay unit 815 includes at least one of one or more reflecting surfaces, a beam splitter, a reflector, a polarizing lens, and an illumination imaging lens relay array, and any of these configured in a desired manner. And a combination.

  The first channel illumination relay unit 815 can collect the light energy emitted from the illumination source 810, and in the first field 830, the first channel light energy sufficient for inspection by the sensor 170 (not shown in FIG. 8). Can be projected downward onto the inspection object 130 in a desired manner. This design can send light energy reflected from the inspection object 130 (ie, the sample under inspection) to the image relay element 815. Another image relay element 855 can collect the reflected light energy and deliver or illuminate the reflected bright field light energy along the image path 805 towards a split readout TDI sensor or dual linear sensor. Can do. The sensor 170 outputs the detected bright field image information from a plurality of readout circuits at point 850. Such a system configuration is well suited for the TDI sensor 700.

  In addition, the second illumination source (not shown) can irradiate light energy or a light flux and send the light energy to the second channel illumination relay unit 820 (that is, the second channel illumination and the imaging lens). The illumination relay unit 820 may include at least one of one or more reflecting surfaces, a beam splitter, a reflector, a polarizing lens, and an illumination imaging lens relay array. The second channel illumination relay unit 820 collects the light energy emitted from the second illumination source, and in the second field 840, the second channel light energy sufficient for the inspection by the sensor 170 is to be inspected in a desired manner. Project to 130. In this configuration, the imaging lens array does not collect light energy at point 895 that reflects from the object 130 (ie, the sample under inspection) in the field 840. The image relay unit 855 collects dark field light energy scattered from the inspection object 130 by illumination.

  The image relay unit 855 collects the scattered light 898 and delivers or projects the received dark field light energy toward a TDI sensor operating in a split mode arrangement, that is, a dual line sensor, simultaneously with the bright field image processing mode. Direct the incident. A sensor (not shown) outputs the detected dark field image processing mode information from a plurality of readout circuits. In this configuration, the design performs simultaneous exposure of the inspection object 130 and provides a bright field response as image data at point 850 and a dark field response as image data at point 860.

  This design uses two different light sources to illuminate the inspection object 130 and move the object in the scanning direction 890 relative to the sensor. The output image data in the bright field moves in the direction 850 opposite to the direction of the target scanning direction 890. Similarly, the output image data of the dark field channel moves in the direction 860 obtained by the mirror / reflecting surface described with reference to FIGS.

  The field division between the bright field illumination 830 and the dark field illumination 840 in the inspection object 130 enables individual filtering processing and additional optical processing to be performed in the image relay system for each of these field regions. . Furthermore, the individual image mode relay mirror array can map an image on one or more sensor arrays, and can individually control the scanning directions 890 of the two regions. Although this embodiment describes the use of bright-field and dark-field image processing modes, those skilled in the art will appreciate that this embodiment can support various optical image processing modes.

  A schematic diagram of an inspection system 900 suitable for simultaneously image processing two non-overlapping field regions of the inspection object 130 in accordance with the second aspect of the design is shown in FIG. In this configuration, a single illumination source and illumination relay system are arranged with a common imaging lens and sensor. The illumination source 910 emits bright-field light energy or light flux, and sends the bright-field light energy toward the first channel illumination relay unit 915 (that is, the first channel illumination and the imaging lens). The first channel illumination relay unit 915 includes one or more reflecting surfaces, a beam splitter, a reflector, a polarizing lens, an illumination imaging lens relay array, and any combination of these configured in a desired manner. Including. The first channel illumination relay unit 915 collects bright field light energy emitted from the illumination source 910 and is sufficient for inspection by the sensor 170 (not shown in FIG. 9) in the first field 930 and the second field 940. The target object 130 is scanned in the direction indicated by 990 while projecting bright field light energy downward onto the object 130 in a desired manner.

  In the description of this design, light energy reflected from the first field 930 and the second field 940 from the inspection object 130 (that is, the sample under inspection) is sent to the image relay unit 915. The image mode relay unit 915 collects the light energy reflected from these fields, and receives the received reflected bright-field light image processing information along the image path 905 toward the bidirectionally divided readout TDI sensor, that is, the dual linear sensor. Deliver or project. The mirror array including the image mode relay units 915 and 955 relays the reflected light energy of the first field 930 and causes it to enter one sensor auxiliary region as the first field image data 950 and at the same time reflect the reflected light of the second field 940. The light energy is relayed and incident on another sensor auxiliary area as second field image data 960.

  The sensor 170 (not shown in FIG. 9) can output a detected image information response from the first field image 950 and generate a signal output in the scanning direction 970 via a plurality of readout circuits. Similarly, the information response from the second field image 960 can generate a signal output in the scanning direction 980 via a plurality of readout circuits.

  In this configuration, this design effectively utilizes all the functions of each sub-array within the split mode TDI sensor, and uses a single illumination source to improve throughput and scan the inspection object 130 faster. it can.

  Yet another aspect of the invention is an inspection method for achieving 100% inspection of an object using two non-overlapping fields and spatially interleaved scans in accordance with the second aspect of the design. 1000 is provided. FIG. 10 shows an inspection method 1000 and a special scanning arrangement sufficient to effectively perform 100% inspection of the inspection object 130. This method is capable of starting the first pass scanning from the right to the left of the inspection object 130 and simultaneously performing the first scanning of the first field 1020 and the second field 1040. When the right-to-left scan reaches the end of the inspection object 130, the scanning process moves in the vertical direction and turns in the opposite direction, starting the second pass scanning from the right to the left of the inspection object 130. To do.

  The inspection method 1000 can provide a mechanism for adjusting a gap existing between fields. This mechanism ensures that the gap between the fields is kept slightly smaller than the height of each field. In the second pass scanning, simultaneous scanning of the first field 1030 and the second field 1050 is executed. The movement and change of scanning direction are performed at point 1025 for the first field and at point 1045 for the second field. When the second pass scanning is completed, the scanning process can return to the origin, that is, the first pass, and the scan pass that is spatially interleaved can be repeated a plurality of times (that is, the third scan, the fourth scan). Etc.) by providing duplication of image processing areas so that the entire inspection object 130 can be sufficiently covered. The inspection method 1000 can perform 100 percent efficient inspection on an inspection object with minimal duplication.

  FIG. 11 shows an outline of an inspection system 1100 according to the third aspect of the present design in which one inspection source 130 is irradiated with one illumination source and two different image processing modes are simultaneously collected from reflected light energy. In this configuration, inspection system 1100 includes a single illumination source (not shown) and an array of two complementary image mode relay elements having a common imaging lens and sensors that collect two different types of illumination. Including. The illumination source emits light energy or light flux and transmits the light energy along path 1110. The illumination relay unit 1115 may include at least one of one or more reflecting surfaces, a beam splitter, a reflector, a polarizing lens, and an illumination imaging lens relay array, and any combination thereof. The illumination relay unit 1115 collects light energy emitted from the illumination source, and inspects the light energy sufficient for inspection by the sensor 170 (not shown in FIG. 11) downward in a desired manner at the field position 1120. While projecting onto the object 130, the inspection object 130 is scanned in the direction 1190.

  In this design, light energy reflected from the inspection object 130 (that is, the sample under inspection) is sent from the field position 1120 to the image relay unit 1155. The image relay unit 1155 collects the light energy reflected from the field position 1120 and transfers or projects the received reflected image processing information along the path 1105 to the bi-directional division readout TDI, that is, the dual linear sensor. The mirror array including the image relay unit 1155 relays the first image mode at the field position 1120 along the path 1105 and sends it as field image data 1130 to the first sensor auxiliary region. Further, the image relay unit 1155 may divide the image near the pupil plane 1155 of the system and separate the reflected light energy. Image segmentation may include separating different types of illumination or image processing modes. The image relay unit 1155 sends the second image light energy to the image relay unit 1160. The image relay unit 1160 collects the light energy reflected from the field position 1120, and transfers or projects the received reflected image processing information along the path 1125 to the bi-directional division readout TDI sensor, that is, the dual linear sensor. The mirror array including the image relay unit 1160 relays the second image mode at the field position 1120 and sends the image mode as the first field image data 1140 along the image path 1125 to the second sensor auxiliary region.

  The sensor 170 (not shown) outputs image information detected from the first image mode 1130 at the field position 1120, and generates a signal output in the scanning direction 1170 via a plurality of readout circuits. Similarly, different image responses are received from field position 1120 using second image mode 1140 and produce a signal output in scan direction 1180 via a plurality of readout circuits (not shown in FIG. 11).

  In this configuration, the design can simultaneously acquire two images from the same field location 1120, and the sensor 170 can process each image individually or in combination. The inspection system 1100 uses a plurality of modes, including but not limited to, including large / small signal readout, multispectral image processing, simultaneous transmission / reflection image processing, and broadband / narrowband optical image processing modes. It may be configured to collect images simultaneously. The inspection system 1100 can include a common optical element in the image processing relay and the image processing mode relay, which is correlated in relative alignment and focus to provide overall stability of the two images. Performance is provided in a manner that is significantly improved compared to utilizing separate optical elements or sensors. In the present embodiment, image information from the same target position may be divided at or near the pupil of the image processing system in order to emphasize or not enhance specific features of each channel.

  One embodiment of the design of FIG. 11 may include a narrowband illumination channel, where the narrowband illumination originates from a broadband illumination source. For example, a mercury xenon lamp is used as an illumination source, and the image relay unit 1160 is appropriately filtered to form i-line wavelength light corresponding to narrowband illumination and broadband illumination. The remaining lamp output can be used. The image relay unit 1160 in such a scenario may include a narrow-band reflection surface, where the narrow-band light energy is used as one inspection channel, and the broadband light energy is transmitted via the image relay unit 1115. Used for other channels. Other forms of splitting lighting are also available.

  FIG. 12 shows an outline of an inspection system 1200 according to the fourth aspect of the present design, which is suitable for simultaneously imaging two non-overlapping field regions of the inspection object 130. In this configuration, the illumination source and the complementary illumination relay system are arranged with a common imaging lens and sensor. The illumination source 1210 emits light energy or light flux and sends the light energy to the illumination relay units 1255 and 1215. The illumination repeaters 1255, 1215 include one or more reflective surfaces, beam splitters, reflectors, polarizing lenses, illuminated imaging lens relay arrays, and any combination of these configured in the desired manner. It's okay. The illumination relay unit 1215 collects light energy emitted from the illumination source 1210, and in the first field 1230 and the second field 1240, provides sufficient light energy for inspection by the sensor 170 (not shown in FIG. 12). The inspection object 130 is scanned in the direction 1290 while projecting downward onto the inspection object 130 in a desired manner.

  This design can transmit light energy reflected or scattered from the inspection object 130 (that is, the sample under inspection) from the first field 1230 and the second field 1240 to the image relay units 1215 and 1255. The image relay unit 1255 can collect the light energy reflected from these fields, and can transfer or project the received image information along the image processing path 1205 to a bi-directional split readout TDI or dual linear sensor. . The mirror array including the image relay unit 1255 relays the light energy reflected by the first field 1230 and makes it incident on one sensor auxiliary area as the first field image data 1250 and simultaneously reflects the light reflected by the second field 1240. The energy can be relayed and incident on the individual sensor auxiliary areas as second field image data 1260. In this arrangement, the design can generate a small overlap 1247 of the inspection region, which overlap 1247 is obtained by including the same region of the inspection object 130 at different times of the first field 1230 and the second field 1240. It is done.

  The sensor 170 (not shown in FIG. 12) can output image information detected from the first field image data 1250 and generate a signal output in the scanning direction 1270 via a plurality of readout circuits. Similarly, the image processing mode information response from the second field image data 1260 can generate a signal output in the scanning direction 1280 of the sensor via a plurality of readout circuits (not shown in FIG. 12).

  In this configuration, the field position is not orthogonal to the scanning direction 1290, and the images of the two inspection areas are relayed to a bidirectional TDI sensor that operates in a split readout mode that captures each image area. Inspection system 1200 provides for 100 percent inspection of the sample to eliminate any gaps between the scanned areas. In this embodiment, the difference in scan time introduced between the two image field regions 1230 and 1240 may be counted in the image processing system 105.

  The foregoing is not intended to determine, limit, or encompass all components, interfaces, communications, and operating modes available for this design. The designs described and the specific aspects described herein are not meant to be limiting and may include alternative components, incorporating the teachings and benefits of the present invention, ie, the present invention, High-speed imaging systems, sensors, and acquisition systems that acquire multiple images or “channels” simultaneously, a semiconductor integrated circuit that meets the full range of inspection requirements for transmitting and reflecting samples in a time and cost efficient manner It realizes the manufacture of. Although the invention has been described with reference to particular embodiments of the invention, it will be understood that the invention is capable of further modifications. This application is intended to cover various variations, uses, or adaptations of the invention in general, according to the principles of the invention, and is a customary example already known in the art to which this invention belongs. Deviations from the present disclosure as categorized as:

It is a block diagram which shows the component and interface of this design in a test | inspection system. FIG. 5 is a flow diagram illustrating an overview of a representative inspection system to describe a feasible implementation that accommodates all aspects of the design. It is a figure which shows typically the conventional bidirectional | two-way delay integration (TDI) sensor. FIG. 2 schematically illustrates a bidirectional TDI sensor configured to operate in a split readout mode according to this design. FIG. 6 is a schematic diagram illustrating an inspection system optical element employing this design operating in the positive direction. FIG. 2 is a schematic diagram illustrating an inspection system optical element employing this design that operates in the reverse direction. FIG. 2 is a schematic diagram illustrating an inspection system optical element employing this design that can operate in both directions. FIG. 6 is a diagram schematically illustrating a dual linear sensor configured to acquire two separate scanned images simultaneously according to the present design. FIG. 6 schematically illustrates a bidirectional TDI sensor configured to utilize different sections for each scanned image region in accordance with the present design. 1 is a schematic diagram illustrating an inspection system configured using two illumination sources and a complementary illumination relay system, along with a common imaging lens and sensor, in accordance with a first aspect of the present design. FIG. FIG. 6 is a schematic diagram illustrating an inspection system configured to simultaneously scan two non-overlapping regions of an object and image them on a sensor according to a second aspect of the design. FIG. 6 is a conceptual diagram illustrating 100% inspection of an object using two non-overlapping fields according to the second aspect of the design. Overview showing an inspection system configured to provide two illumination modes using one illumination source, two image relays, a common imaging lens, and a sensor according to a third aspect of the design FIG. FIG. 7 is a schematic diagram illustrating an inspection system configured to simultaneously scan two non-overlapping field regions of an object and image them on a sensor according to a fourth aspect of the design.

Claims (22)

A method for performing a dual channel inspection of at least one region of a sample, comprising:
A plurality of channels of light incident from the at least one region of the sample are integrated in a direction from the center of the light receiving surface to the first side of the light receiving surface of a single TDI sensor . When the first detection region and the second detection region in which the direction from the center of the light receiving surface toward the second side opposite to the first side is determined as the integration direction ,
The movement direction of the sample image on the light receiving surface, which is moved in accordance with the movement of the sample, is the light of one channel incident on the first detection region and the light of another channel incident on the second detection region. Unlike in the said one direction of movement of the sample image by the light channels is an integration direction of the first detection area, the integration direction of movement of the sample image by light of the other channels of the second sensing region and such so that the direction, the direction of light of said one channel, along with changing the direction of light in the other channel,
A method of simultaneously supplying the light of the one channel and the light of the other channel to the light receiving surface. The method according to claim 1, wherein after the simultaneous supply, data representing the light of the one channel and the light of the other channel is transmitted simultaneously from the TDI sensor. The light of the one channel is transmitted to at least one first reflecting surface, and the light of the other channel is transmitted to at least one second reflecting surface, thereby transmitting the light of the one channel and the other channel. The method according to claim 1 , wherein a moving direction of the sample image on the light receiving surface is different from that of the channel light . The light incident from one region of the sample is received as a first channel and the light incident from the second region of the sample is received as a second channel when receiving light on the light receiving surface. The method according to 1. When receiving light on the light receiving surface, light having one characteristic is received as a first channel from one area of the sample, and light having another characteristic is received as a second channel from the one area. The method according to claim 1 , wherein the method receives light . 6. The method of claim 5 , wherein the one feature includes bright field illumination and the second feature includes dark field illumination . When receiving light on the light receiving surface, light having one characteristic is received as a first channel from one area of the sample, and light having another characteristic is received as a second channel from another area. The method of claim 1. A single TDI sensor configured to receive light for the purpose of inspecting a sample,
A first detection in which the direction from the center of the light receiving surface toward the first side of the light receiving surface is determined as an integration direction so as to receive image data generated based on the light of the first channel received from the sample A direction from the center of the light receiving surface toward the second side opposite to the first side so as to receive the image data generated based on the region and the light of the second channel received from the sample A light-receiving surface comprising: a second detection region defined in the integration direction;
A first readout circuit connected to a first side of the first detection region and configured to read out image data of the first channel from the TDI sensor;
Connected to the second side of the second detection area, and configured to read the image data of the second channel from the TDI sensor simultaneously with the reading of the image data of the first channel from the TDI sensor. A second readout circuit,
The movement direction of the sample image on the light-receiving surface moved in accordance with the movement of the sample differs depending on the light of each channel, and the movement direction of the sample image by the light of the first channel incident on the first detection region is different. The first and the second detection areas are integrated so that the moving direction of the sample image by the light of the second channel incident on the second detection area becomes the integration direction of the second detection area. A TDI sensor in which light of a second channel is incident on the light receiving surface. The sensor according to claim 8, wherein the first detection region includes a line. The sensor according to claim 9, wherein the second detection region includes a line . A system for performing simultaneous dual channel inspection of a sample,
At least one illumination device configured to supply light to the sample;
A first detection region in which a direction from the center of the light receiving surface toward the first side of the light receiving surface is determined as an integration direction, and a second side opposite to the first side from the center of the light receiving surface. A light-receiving surface comprising a second detection region whose direction is defined as an integration direction; a first readout circuit connected to the first side; and a second readout side connected to the second side. A single TDI sensor comprising: a second readout circuit configured to read out image data simultaneously with the one readout circuit;
Receives light from two channels from the sample, and changes the moving direction of the sample image on the light receiving surface, which is moved as the sample moves, to the integration direction of the first detection region. And an orientation optical element that moves the sample image along the integration direction of the second detection region, does not change the movement direction of the sample image of the light of the other channel, and
With
The TDI sensor receives and processes simultaneously the light energy of the channel whose movement direction has been changed and the light energy of the channel whose movement direction is not changed. The orientation optical element is
At least one lens;
12. The system of claim 11, comprising at least one reflective surface. 13. The set of reflective surfaces according to claim 12, further comprising a set of insertable reflective surfaces configured to provide an alternative path for changing the direction of movement of a sample image formed on the TDI sensor. The described system. The at least one illumination device includes a bright field illumination device and a dark field illumination device, and the two channels of light received from the sample include a bright field illumination light channel and a dark field illumination light channel. The system according to claim 11 . An optical element is further included between the at least one element and the sample, the optical element supplying light having one characteristic to the sample and light having a second characteristic to the sample. The system of claim 11 , configured as follows. The system of claim 15, wherein the first feature includes a first wavelength and the second feature includes a second wavelength . The system of claim 15 , wherein the first feature includes a first polarization and the second feature includes a second polarization . The system of claim 11 , wherein the size of the first detection region is different from the second detection region, and different size regions improve control of dynamic range and sensitivity . The system of claim 11 , wherein a size of the first detection area is substantially the same as a size of the second detection area . The system of claim 11 , wherein the at least one lighting device includes a narrowband lighting device and a broadband lighting device . The at least one illumination device includes a narrowband illumination device, and the orientation optical element is configured to filter narrowband illumination from the narrowband illumination device to broadband illumination. The system of claim 11 , comprising: Said narrow band illumination device comprises a mercury-xenon lamp, the alignment optical element, using at least one narrow band reflecting surfaces, for separating the wavelength energy of i- line from the mercury-xenon lamp, to claim 21 The described system.

Images